This invention relates generally to the provision of lightweight, fireproof roofing shakes, capable of withstanding installation and foot traffic, and without breakage, as well as wind up-lift forces, and more particularly concerns cementitious admixtures from which such roofing pieces are formed.
There is continuous need for improvements in lightweight cementitious shakes, and their installation, for example to prevent breakage during such installation, and thereafter, and to prevent up-lift due to wind.
Current lightweight concrete and fiber cement roof shakes and shingles are produced in flat sheets or continuous taper shapes. These shapes do not lay flat when installed and must flex when installed or walked upon. Necessary flexural strength is obtained using high density and therefore heavy materials in a thin (1/4 to 3/8 inch thickness) section or low density lighter materials in a thicker (approximately 3/4 inch thickness) section. The thin section materials suffer from low market appeal and the thicker section materials are not thick enough and suffer also from excessive breakage during application and underfoot traffic.
Existing alternate material shakes used to replace traditional wood shakes to provide fire safety, are made in 22 inch long by 12 inch maximum width shapes. These shakes are installed with a 10 inch exposure often over spaced sheathing boards which are on 11 inch centers making adjustment of the nailing point necessary. Additionally, from 120 to 150 shakes must be installed to cover 100 square feet of roof surface (1 roofing square).
It is the object of this invention to create a new shape which, when installed in a full double overlap shingled method, lays flat and can, therefore, be made very thick (up to 11/2 inches) using a very lightweight cementitious material (or other suitable material) which can be formed by standard extrusion or pressure/vibration tile, paver or block forming machines. Additionally, nail points are pre-marked in two, separate locations to provide for normal wind up-lift forces and for very high wind up-lift forces.
It is yet another object to produce shakes of minimum 23 inches long and minimum 121/2 inches wide size to allow for 11 inch exposure installation and 11 inch on center nailing points and 100 or less shakes per roofing square.
Prior roofing shakes or shingles and methods of production are disclosed, for example, in Jakel U.S. Pat. No. 3,841,885, Jakel U.S. Pat. No. 3,870,777, Kirkhuff U.S. Pat. No. 3,852,934 and Murdock U.S. Pat. No. 4,288,959, and Wood U.S. Pat. No. 4,673,659 describing problems encountered in lightweight extruded tile production.